mdss: Fix solid fill unpack pattern

Most users expect RGB order instead of RBG.
When userspace gives an ARGB color, the blue and green
channels are swapped.
Adjust pattern to match ARGB instead of ARBG.

CRs-Fixed: 1045472 1084507
Change-Id: I413ded858df41496d26362602abf3eb40c3cc1ed
Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>